We present a new type of self-imaging phenomenon: self-imaging along curved trajectories. Unlike the Talbot effect, where self-imaging occurs for periodic wave patterns propagating along a straight line, here the field is generally not periodic and is self-imaged along curved trajectories. In the paraxial regime, self-imaging along a parabolic trajectory can ideally go on indefinitely. In the nonparaxial regime the self-imaging is along a circular trajectory and lasts as long as the beam bends. We demonstrate this accelerating self-imaging effect experimentally, and discuss generalizations to higher dimensions.
Medical ultrasound and optoacoustic (photoacoustic) imaging commonly rely on the concepts of beam-forming and tomography for image formation, enabled by piezoelectric array transducers whose element size is comparable to the desired resolution. However, the tomographic measurement of acoustic signals becomes increasingly impractical for resolutions beyond 100 µm due to the reduced efficiency of piezoelectric elements upon miniaturization. For higher resolutions, a microscopy approach is preferred, in which a single focused ultrasound transducer images the object point-by-point, but the bulky apparatus and long acquisition time of this approach limit clinical applications. In this work, we demonstrate a miniaturized acoustic detector capable of tomographic imaging with spread functions whose width is below 20 µm. The detector is based on an optical resonator fabricated in a silicon-photonics platform coated by a sensitivity-enhancing elastomer, which also effectively eliminates the parasitic effect of surface acoustic waves. The detector is demonstrated in vivo in high-resolution optoacoustic tomography.
Optical imaging is commonly performed with either a camera and wide-field illumination or with a single detector and a scanning collimated beam; unfortunately, these options do not exist at all wavelengths. Single-pixel imaging offers an alternative that can be performed with a single detector and wide-field illumination, potentially enabling imaging applications in which the detection and illumination technologies are immature. However, single-pixel imaging currently suffers from low imaging rates owing to its reliance on configurable spatial light modulators, generally limited to 22 kHz rates. We develop an approach for rapid single-pixel imaging which relies on cyclic patterns coded onto a spinning mask and demonstrate it for in vivo imaging of C. elegans worms. Spatial modulation rates of up to 2.4 MHz, imaging rates of up to 72 fps, and image-reconstruction times of down to 1.5 ms are reported, enabling real-time visualization of dynamic objects.
Objectives The mRNA-based COVID-19 vaccines are now employed globally and have shown high efficacy in preventing SARS-CoV-2 infection. However, less is known about the vaccine efficacy in immune suppressed individuals. This study sought to explore whether humoral immunity to the COVID-19 vaccine BNT162b2 is altered in rheumatoid arthritis patients treated with Janus kinase inhibitors by analyzing antibodies titer, neutralization activity and B cell responses. Methods We collected plasma samples from 12 rheumatoid arthritis patients who were treated with Janus kinase inhibitors and received two doses of the BNT162b2 vaccine, as well as 26 healthy individuals who were vaccinated with the same vaccine. We analyzed the quantity of the anti-spike IgG and IgA antibodies that were elicited following the BNT162b2 vaccination, the plasma neutralization capacity and the responsiveness of the B-lymphocytes. We used ELISA to quantify antibody titers, and plasma neutralization assay was used to determine virus neutralization capacity. Alteration in expression of genes that are associated with B cell activation and germinal center response were analyzed by qPCR. Results Reduced levels of anti-spike IgG antibodies and neutralization capacity were seen in the rheumatoid arthritis patients who were treated with JAK inhibitors in comparison with healthy individuals. Furthermore, B cell responsiveness to the SARS-CoV-2 spike protein were reduced in the rheumatoid arthritis patients. Conclusion Rheumatoid arthritis patients who are treated with JAK inhibitors show suppressed humoral response following BNT162b2 vaccination, as revealed by the quantity and quality of the anti-spike antibodies.
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